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Come see horticulture on display March 19-20 at the 2010 All-Iowa Horticulture Exposition

March 16, 2010

The Iowa State Horticultural Society will again host the All-Iowa Horticulture Exposition this coming Friday and Saturday (March 19-20) at the new Bridge View Conference Center in Ottumwa, Iowa. You may receive 0.5 GCSAA CEU’s for Friday’s sessions and 0.4 GCSAA CEU’s for Saturday’s sessions. If you need points to keep your classification or certification this would be a great time to pick up additional education relevant to your profession. No pre-registration is needed. On-site registration starts at 9:00 A.M. on Friday and 8:30 A.M. on Saturday. Live radio and television coverage will be part of this event with many other demonstrations on the trade floor. More information may be attained by going to the website or by calling 641-683-6260.

2010 alliowahorbrochure (3)

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Responsible Phosphorus Use in Iowa

May 30, 2014

Phosphorus (P) is an essential macronutrient that all plants need in relatively large quantities. The amount of P fertilizer needed by turfgrass is usually significantly less than nitrogen or potassium. However, P is particularly important during early grass seedling growth and development stages.  Phosphorus plays a role in establishment, rooting, maturation, growth, and reproduction of plants. Plants can extract the relatively immobile soil P as dihydrogen phosphate (H2PO4-) or hydrogen phosphate (HPO4-2). The terms available phosphate, available phosphorus, available phosphoric acid, and P2O5may be used to refer to phosphorus fertilization.

While P is an important nutrient for grasses and other plants, it is also a vital nutrient for algae and weeds in our lake systems. Phosphorus is usually the least abundant nutrient in freshwater lakes, and is often a limiting factor for the growth of algae and weeds. Lake enrichment of P can cause undesirable algal blooms and increased aquatic weed pressure, a process termed eutrophication. A result of eutrophication is an environment unsuitable for many fish and wildlife inhabitants. 

Turfgrass P deficiencies are usually first recognized by stunted growth and reduced seedling vigor. It is unusual to see a P deficiency in a mature plant. In addition to the reduced growth, leaf blades can turn a purple to reddish color. The turf stand will begin to decline in quality, if the deficiency is not addressed.

Most soils in Iowa contain adequate amounts of phosphorus and no additional phosphorus should be used in a fertilizer program unless indicated by a low soil test. A 1.0 lb. of P205 per 1000sq. ft. is permitted for establishment purposes; however, it is still strongly recommended that this application follow a low soil phosphorus determination.

Recent regulations in Minnesota and Wisconsin restrict residential landscapes phosphorus applications in an effort to minimize environmental threats. While there are no phosphorus restrictions in Iowa, phosphorus should only be applied when a soil test has indicated a need for additional amounts. The Iowa Professional Lawn Care Association (IPLCA) has placed a self-enforced restriction on the use of P fertilizers on lawns surrounding lakes and other waterways. They will use P containing fertilizers in these areas only at the time of establishment. They are also careful to remove all fertilizer from hard surfaces to prevent movement into sanitary sewer systems.

The entire extension publication is attached in pdf form.  To download the publication, click on the following link Phosphorus Publication.   



October 2, 2014

On April 2, 2014, I posted some information on the very cold winter that we had just emerged from and its affect on warm- and cool-season grasses. It was the 9th coldest winter in 141 years.   This summer was surprisingly wet and mild and the cool-season grasses recovered fine.  The big question this season was how would the warm-season grasses like bermudagrass (Cynodon spp) and windmill grass (Chloris verticullata) that have moved into our region in recent years.  These species are very susceptible to cold and I had speculated that their populations would be greatly diminished by the cold winter.

I was wrong.  Both bermudagrass and windmill grass survived just fine.  This is a bit confusing.  We have assumed that it was our cold winters that kept these species from being a problem in the past and that the recent warm winters were the cause of their increase in the region.  If that were the case, a very cold winter should have killed them.

In the case of windmill grass, it could be the fact that seed had built up in the soil and that germination during the summer was the cause of its return.  That is not what I have observed, the stolons from last year recovered.  Likewise, bermudagrass came back form plant parts.

I can only speculate that it would take a series of cold winters to eliminate these grasses from the region.  It is something that I will keep track of the next few years. They are likely here to stay.

Windmill grass seedhead.

 Windmillgrass in central Iowa lawn.

Bermudagrass incentral Iowa lawns (nest two pictures.